By Parisa Hafezi | ANKARAPresidentHassan Rouhani cast his hardline clerical opponents as power-hungry pawns of Iran's security forces on Friday, going far beyond the traditional bounds of Iranian political discourse in a blistering final TV debate a week before an election.Rouhani, first elected in a landslide four years ago on a promise to reduce Iran's international isolation, is trying to hold on to office by firing up reformist voters disillusioned by a stalled economy and the slow pace of social reform.Although he has long cast himself as an insider and pragmatist rather than a gung-ho reformer, he seems to have shed that moderate image in recent days, seeking to energize voters who want less confrontation abroad and more freedom at home.In three hours of blazing exchanges with his rivals, he took on targets once seen as all but untouchable, including the judicial establishment and the Revolutionary Guards, the elite military force that controls much of Iran's economy."Mr. Raisi, you can slander me as much you wish. As a judge of the clerical court, you can even issue an arrest order. But please don't abuse religion for power," Rouhani said at one point to his main hardline rival, Ebrahim Raisi, a judicial official and protege of Supreme LeaderAyatollah Ali Khamenei."Some security and revolutionary groups are busing people to your campaign rallies ... Who finances them?" said Rouhani at another point.He cast his other main rival, Tehran Mayor Mohammad Baqer Qalibaf, a former Guards commander and police chief, as a thug who had boasted of personally taking on young demonstrators."You wanted to beat up students," Rouhani said.The two main rivals mostly hammered Rouhani's record on the economy, arguing that jobs have been lost and prices have risen despite the 2015 agreement Rouhani reached with global powers to lift sanctions in return for curbing Iran's nuclear program.Raisi said 250,000 small businesses had shut and cash payments to the poor should be raised: "Unemployment is high. People's purchasing power has dropped dramatically," he said.But even on the economy, Rouhani responded with a thinly-veiled swipe at the Revolutionary Guards: "If we want a better economy, we should not let groups with security and political backing to get involved in the economy," he said.Although Iran's political system puts ultimate power in the hands of the unelected supreme leader and all candidates are vetted by a hardline watchdog body, elections are nevertheless hard-fought contests that can bring dramatic change.Normally measured in his public speeches, Rouhani has become increasingly forceful in recent days, giving voice to the grievances of reformers who say they have been oppressed since the 1979 Islamic Revolution by security forces like the Guards."I am surprised. Those of you who talk about freedom of speech these days... (you are) those who cut out tongues and sewed mouths shut," he told a rally on Monday in a barely disguised attack on Raisi, who was one of four judges that ordered mass executions of political prisoners in the 1980s.REACHING OUTRouhani's biggest worry is that some of the voters who carried him to a single-round victory in 2013 will stay home, disillusioned that the lifting of sanctions has brought few economic benefits and the pace of social change has been slow."Rouhani is trying to reach out to voters who guaranteed his election four years ago by hoping to have a freer Iran," said a former official close to Rouhani's government.The message appears to be getting through, with Rouhani's rallies attracting chants of reformist slogans. Voters who had grown cool say they are now taking the election seriously."I wanted to boycott this election because I am so disappointed with Rouhani's failure to bring more freedom to Iran," said teacher Reza Mirsadegh in the central city of Yazd."But I have changed my mind. I will vote for Rouhani to prevent Raisi's win."Rouhani's 2015 deal to lift sanctions won the official backing of Khamenei, but the leader and his hardline loyalists have since criticized its failure to boost the economy.Benefits have been slow to arrive, in part because of unilateral U.S. sanctions still in place over Iran's missile program, human rights record and Washington's accusations that Tehran supports terrorism."Dear people of Iran, vote for freedom ... I am ready to get the remaining sanctions lifted if elected," Rouhani said. Lifting the remaining sanctions would be difficult, as Khamenei, who has the last say on all state matters, has flatly rejected normalization of ties with the United States.The Guards, their affiliated volunteer Basij militia and many Friday prayer leaders have thrown their support behind Raisi, a veteran jurist whose name has also been mentioned as a future supreme leader.Qalibaf, a chisel-jawed former Guards commander, lacks Raisi's backing from the clerical establishment but also has millions of supporters for a hardline message on security and a populist economic platform.If no candidate wins 50 percent of the vote on May 19, a second round run-off would be held a week later. Qalibaf has made a run-off more likely by resisting calls from other hardliners to step aside.(Writing by Parisa Hafezi; editing by Peter Graff) --- ---...